This document describes the simulation principle, outlines the design procedure of the projection optics system from predesign to achromatization. The Optical system collimates output from Liquid crystal light valve in 8~12μm and enables an imaging system to be tested out of 20°field of view. The effective focal length of this F/1.5 system is about 113mm. There is sufficient exit pupil distance to match projector exit pupil to the LWIR imagery system entrance pupil. A long working distance between Liquid crystal light valve and the optics system is approximately 120mm. The Modulation Transfer Function (MTF) and the geometric blur spot for three-field position repenting an on-axis point, a full field and an intermediate point show the better performance of the optical system.